Background: Microbial organisms are normally present on human eyelashes. Application of mascara to lashes has the potential to inoculate the mascara tube with microbes. This pilot study of a real-world situation investigated the microbial contamination of 2 brands of mascara used daily for 3 months.
Methods: Forty women between the ages of 18 and 39 were randomly assigned to use 1 of 2 brands of nonwaterproof mascara. All mascara tubes were unexpired and purchased on the same day. Subjects were instructed to use the mascara on both the upper and lower lids every day for 3 months. After 3 months, the mascara tubes were collected, cultured, and examined for microbial growth.
Results: Mascara tubes were collected from 33 of 40 (82.5%) subjects who began the study. Microbial growth was found in 36.4% of the subject tubes. Based on growth on selective media, most of the organisms were determined to be Staphylococcus epidermidis, Streptococcus species, or fungi. We did not attempt to quantify the numbers of bacteria or fungi present within the tubes.
Conclusions: Because microbial presence was found in 36.4% of the mascara tubes cultured after 3 months of use, we recommend a maximum 3-month use of a mascara tube used on a daily basis. More frequent replacement may be warranted with further study.